The invention relates to a process for the preparation of catalysts comprising one or more sulfides of metals selected from the group consisting of nickel, cobalt, molybdenum and tungsten on a porous carrier. The invention further relates to the use of these catalysts for the conversion of hydrocarbon mixtures.
Catalysts comprising one or more sulfides of the above-mentioned metals on a porous carrier are well-known and are used on a large scale for the conversion of sulfur-containing hydrocarbon mixtures in the presence of hydrogen. As a rule these catalysts are prepared by contacting a porous carrier with an aqueous solution of salts of the metals concerned, followed by drying, calcining and sulfiding of the composition.
According to Netherlands patent application No. 72.11116, catalysts of the above-mentioned type with improved activity for the conversion of hydrocarbon mixtures in the presence of hydrogen can be obtained, if the preparation is carried out as follows. First of all a composition is prepared comprising a porous carrier, one or more water-soluble salts of the above-mentioned metals and a specific amount of water. Subsequently, this composition is treated at a temperature below 150.degree.C with a hydrogen sulfide-containing gas. Finally the material is heated in a hydrogen-containing gas to a temperature above 200.degree.C. The amount of water which should be present in the composition to be treated with the hydrogen sulfide-containing gas corresponds to the amount of water present in the composition after the latter has been dried in a dry gas at 110.degree.C, increased by 20-120% of the amount of water which the said dried composition is capable of taking up within the pores of the carrier at 20.degree.C. In addition to the advantage that the process described in the Netherlands patent application, compared with conventional catalyst preparation methods, enables the preparation of catalysts with improved activity for the conversion of sulfur-containing hydrocarbon mixtures in the presence of hydrogen, the process enables a considerable part of the catalyst preparation to be carried out in the hydrocarbon conversion reactor as part of the start-up of the hydrocarbon conversion process in which the catalyst is applied.
The wet sulfiding technique described in said Netherlands patent application has two drawbacks. The first drawback relates to the above-mentioned embodiment of the process in which a considerable part of the catalyst preparation is carried out as part of the start-up of the hydrocarbon conversion process in which the catalyst is applied. In this embodiment considerable quantities of decomposition products originating from the metal salts find their way into the reactor system. The second drawback is of more general character and relates to the fact that the process cannot be applied to catalyst materials which have already been subjected to a calcining treatment. This is rather a serious limitation of the process, since catalyst materials are usually commercially available in calcined form.
Further research into the application of the wet sulfiding technique in the catalyst preparation has now led to the development of a process by which catalysts can be prepared, the activity of which for the conversion of hydrocarbon mixtures in the presence of hydrogen is at the same high level as that of the catalysts prepared according to the said Netherlands patent application, but which process does not have the drawbacks described above.